Multiple images (also referred to as frames) are combined after they have been aligned to a reference frame, for applications such as high dynamic range (HDR) photography, noise filtering and others. High dynamic range photography is a process for representing a greater range of luminance levels in an image than can be achieved using traditional digital or analog photography. For example HDR images can represent real-world scenes containing both heavy shade and bright sunlight. Noise filtering by combining multiple images comprises computing an aggregation of many frames depicting the same scene in a manner so as to reduce the amount of noise in the output image.
Multiple images or frames are increasingly available from camera phones, web cameras, and other types of cameras. For example, bracketing whereby a plurality of frames are captured using different camera parameters for different ones of the frames is often used for HDR photography. For example, burst photography, whereby a plurality of frames are captured rapidly in a temporal sequence is available on many camera phones.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known systems for combining images.